Oracle Message ORA-15033 - disk string belongs to diskgroup string

ERRORdisk string belongs to diskgroup string
CAUSEAn attempt was made to ADD to a diskgroup a disk that was already part of another diskgroup, or an attempt was made to DROP / OFFLINE / ONLINE / CHECK a disk that was not part of the specified diskgroup.
ACTIONFor ADD, check the path specifier for the disk. If it is certain that the disk is not in use by another diskgroup, the FORCE option may be used to override this check. For the other commands, check the name of the specified disk.